Thorax Flashcards
What is the thorax, and where is it located?
The thorax is the part of the body between the neck and abdomen, commonly referred to as the chest.
How does the thorax differ from the chest?
The term “chest” is broader and includes more structures than the thoracic wall and cavity, such as the pectoral girdle and breast tissue.
What are the major functions of the thoracic cavity?
The thoracic cavity houses organs of the respiratory and cardiovascular systems, provides protection for vital organs, and facilitates breathing.
How is the thoracic cavity divided?
It is divided into the mediastinum, which contains the heart and other structures, and two pulmonary cavities that house the lungs.
What organs occupy the pulmonary cavities in the thorax?
The lungs occupy the pulmonary cavities.
What is the mediastinum, and what does it contain?
The mediastinum is the central compartment of the thoracic cavity, containing the heart, esophagus, trachea, and major blood vessels.
What is the shape of the thoracic cavity, and how does it change from top to bottom?
The thoracic cavity is shaped like a truncated cone, narrowing superiorly and widening inferiorly.
What bones form the pectoral girdle?
The pectoral girdle is formed by the clavicles and scapulae.
What is the thoracic skeleton composed of?
It is composed of 12 pairs of ribs, the sternum, and 12 thoracic vertebrae with their intervertebral discs.
How does the thoracic wall protect abdominal organs?
The lower half of the thoracic wall surrounds and protects some abdominal viscera, such as the liver.
What is the relationship between the thoracic diaphragm and the thoracic cavity?
The diaphragm forms the floor of the thoracic cavity, separating it from the abdominal cavity.
What are the functions of the lungs?
The lungs provide for the exchange of oxygen and carbon dioxide between the air and the blood.
How do nutrients traverse the thoracic cavity?
Nutrients pass through the thoracic cavity via the esophagus, traveling from the head to the abdomen.
Why are the mammary glands discussed in the context of the thorax?
Although functionally related to the reproductive system, the mammary glands are located on the thoracic wall.
What constitutes the true thoracic wall?
The true thoracic wall includes the thoracic cage, muscles, skin, subcutaneous tissue, and fascia.
Where are the mammary glands located?
They lie within the subcutaneous tissue of the thoracic wall
What is the function of the thoracic cage?
It protects vital organs, supports the upper limbs, and provides attachment for various muscles.
How do ribs contribute to the structure of the thoracic wall?
Ribs form the main structure of the thoracic wall, providing rigidity and protection.
What is the significance of the thoracic cage’s joints?
The joints allow for movement and flexibility, which are essential for breathing.
How do changes in the shape of the thoracic cage support respiration?
Movements of the thoracic cage during breathing change the volume of the thoracic cavity, aiding air exchange.
What factors contribute to the rigidity of the thoracic cage?
Its shape and osteocartilaginous elements contribute to rigidity, while joints and flexible ribs allow for movement.
How do intercostal spaces support the function of the thorax?
They contain muscles, nerves, and vessels that assist in respiration and other functions.
What are the types of ribs found in the thoracic skeleton?
There are true ribs (1-7), false ribs (8-10), and floating ribs (11-12).
How are typical ribs different from atypical ribs?
Typical ribs (3-9) share common structural features, while atypical ribs (1, 2, 10-12) have unique characteristics.
What features are common to typical ribs?
Typical ribs have a head, neck, tubercle, and body with a costal groove for neurovascular protection.
How do false ribs differ from true ribs?
False ribs connect indirectly to the sternum via the costal cartilage of the rib above them.
What characterizes floating ribs?
Floating ribs do not connect to the sternum or other ribs anteriorly; their ends are embedded in muscle.
What is the function of costal cartilages in the thorax?
They provide flexibility to the thoracic wall, allowing movement and expansion during breathing.
How are intercostal spaces named and organized?
They are named for the rib forming their superior boundary, with 11 spaces in total.
What structures occupy the intercostal spaces?
Intercostal spaces contain muscles, membranes, blood vessels, and nerves.
What are the key features of thoracic vertebrae?
Thoracic vertebrae have costal facets for rib attachment and long, downward-sloping spinous processes.
How do costal facets on thoracic vertebrae facilitate rib attachment?
They allow ribs to articulate with the vertebrae at joints of the head of the rib and costotransverse joints.
What is the sternum, and what are its parts?
The sternum is a flat bone located in the anterior thorax, consisting of the manubrium, body, and xiphoid process.
What is the function of the xiphoid process in the sternum?
It serves as a landmark for the inferior border of the heart and attachment for the diaphragm and abdominal muscles.
What are the superior and inferior thoracic apertures?
They are openings at the top and bottom of the thoracic cage that allow passage of structures between the thorax, neck, and abdomen.
What structures pass through the superior thoracic aperture?
The trachea, esophagus, nerves, and blood vessels that supply the head, neck, and upper limbs.
How does the diaphragm separate the thoracic and abdominal cavities?
It completely occludes the inferior thoracic aperture and controls the volume of the thoracic cavity.
What is the role of the diaphragm in breathing?
The diaphragm contracts to increase the vertical dimension of the thoracic cavity during inspiration.
How does the thoracic cavity change during inspiration?
The volume increases as the thoracic wall expands and the diaphragm contracts.
What happens to the thoracic cavity during expiration?
The volume decreases due to the elastic recoil of the lungs and relaxation of respiratory muscles.
How do the pump-handle and bucket-handle movements aid respiration?
Pump-handle movement increases the anteroposterior dimension, while bucket-handle movement increases the transverse dimension.
What is the clinical significance of the superior thoracic aperture?
It can be a site of compression or obstruction affecting structures such as the brachial plexus and subclavian vessels.
How do ribs move during breathing?
They elevate during inspiration and depress during expiration, increasing and decreasing thoracic volume.
What are costovertebral joints?
They are joints where the heads of the ribs articulate with the bodies of thoracic vertebrae.
What ligaments support costovertebral joints?
Ligaments such as the radiate ligament and the intra-articular ligament.
How are costotransverse joints structured?
They form between the tubercle of the rib and the transverse process of the vertebra.
What is the function of the sternocostal joints?
They connect the ribs to the sternum, allowing for movement during breathing.
What distinguishes the manubriosternal joint from other sternal joints?
It is a cartilaginous joint that may fuse with age, forming the sternal angle.
What types of movement occur at costotransverse joints?
Rotation and gliding movements, allowing rib elevation and depression.
How do the true muscles of the thoracic wall differ from accessory muscles?
True thoracic muscles are directly involved in moving the thoracic cage, while accessory muscles assist during deep or forceful respiration.
What is the role of the pectoralis muscles in respiration?
They can act as accessory muscles, helping to elevate the ribs during deep breathing.
How do the scalene muscles contribute to thoracic movement?
They stabilize the first two ribs, enabling other muscles to elevate the lower ribs during inspiration.
What are the main muscles that occupy the intercostal spaces?
The external, internal, and innermost intercostal muscles.
How do the external intercostal muscles contribute to respiration?
They elevate the ribs during inspiration, increasing the thoracic cavity’s volume.
What is the function of the internal intercostal muscles?
They depress the ribs during forced expiration, decreasing thoracic cavity volume.
How do the serratus posterior muscles influence thoracic movements?
They are thought to have a proprioceptive function rather than a primary role in respiration.
What is the proprioceptive function of the thoracic wall muscles?
These muscles may help sense the position and movement of the thoracic cage.
What are the functions of the levatores costarum muscles?
They assist in rib elevation, although their role in normal respiration is not well established.
What structures are attached to the xiphoid process?
The diaphragm, rectus abdominis muscle, and transversus thoracis muscles attach to the xiphoid process
Why are rib fractures more common in the middle ribs than in the upper or lower ribs?
The middle ribs are more exposed and less protected by the pectoral and scapular muscles.
What is the clinical consequence of rib fractures?
Rib fractures can cause significant pain, restrict breathing, and potentially damage internal organs.
What is a flail chest, and how does it affect breathing?
Flail chest occurs when multiple rib fractures allow a portion of the thoracic wall to move independently, leading to paradoxical movements that impair ventilation.
What is thoracotomy, and why is it performed?
Thoracotomy is a surgical procedure to access the thoracic cavity, often for lung or heart surgery
What is a median sternotomy, and when is it used?
It involves splitting the sternum along the midline to access the thoracic cavity, typically used in cardiac surgery.
Why might the sternum be used for bone marrow biopsies?
The sternum’s subcutaneous position and vascular spongy bone make it accessible for sampling.
What developmental anomalies can affect the sternum?
Conditions like pectus excavatum (sunken chest) or pectus carinatum (protruding chest) can occur if the sternum’s halves do not fuse properly.
How can the superior thoracic aperture lead to thoracic outlet syndrome?
Compression of nerves or blood vessels passing through the superior thoracic aperture can cause symptoms in the upper limbs.
What is rib dislocation, and what are its common symptoms?
Rib dislocation occurs when the costal cartilage separates from the sternum, leading to localized pain and deformity.
What can cause separation of the costochondral joints?
Trauma or severe stress to the rib cage can cause these joints to separate, resulting in pain and instability.
What are the consequences of diaphragm paralysis?
Paralysis causes paradoxical movement, impairing the efficiency of breathing.
How do the thoracic nerves contribute to the innervation of the thoracic wall?
Thoracic nerves provide motor and sensory innervation to the intercostal muscles, skin, and parietal pleura.
What is the significance of the costal groove on a rib?
It protects the intercostal nerves and vessels running along the rib.
What are intercostal spaces, and what do they contain?
Intercostal spaces are gaps between adjacent ribs, containing muscles, nerves, and vessels.
How do the movements of the thoracic wall affect lung pressures?
Expansion decreases intrapulmonary pressure, drawing air in, while compression increases pressure, expelling air.
What is the “bucket-handle” movement, and how does it contribute to breathing?
This lateral rib elevation increases the thoracic cavity’s transverse diameter.
What is the “pump-handle” movement, and how does it contribute to breathing?
This anterior rib elevation increases the thoracic cavity’s anteroposterior diameter.
What is the function of the intercostal muscles during normal and forced breathing?
They stabilize the thoracic wall during quiet breathing and elevate or depress ribs during forced respiration.
What is the anatomical arrangement of the intercostal nerves and vessels?
They run along the costal groove on the inferior border of the rib
What structures pass through the openings in the diaphragm?
The aorta, esophagus, and inferior vena cava pass through the diaphragm.
What is thoracic outlet syndrome, and what are the common symptoms?
It is a condition where nerves or blood vessels are compressed, leading to pain, numbness, or weakness in the upper limbs
